Ontario's Plain-English Guide to Custom Home Buildingπ 705-533-1633 | βοΈ 1-866-868-6606 | βοΈ info@icfhome.ca
The Best Heat Source for Radiant Floors in Ontario (2026): Condensing Boiler, Combi, Air-to-Water, Geothermal or Electric Boiler, by Cost, Running Cost and Cooling
Heating, Cooling & Ventilation
What Should Heat the Water in Your Radiant Floor: Five Choices, What Each Costs to Buy and Run, and the One I Would Pick for a Tight House
I have been putting tubing in floors since the early 1990s, and the floor is the easy part. The question that keeps people up at night is what heats the water. The tubing does not care; it will carry warm water from a boiler, a heat pump or a hole in the ground with equal indifference. What changes is the installed price, the monthly bill, whether the same equipment can cool the house in July, and how much of your mechanical room it eats. Here are the five real choices for an Ontario house, priced and run through the same arithmetic.
The Five Choices on One Table
Running cost here is for a house that needs 18,000 kWh of delivered heat a year, with gas at $0.45 a cubic metre all-in, electricity at 16 cents a kWh all-in, and propane at $0.90 a litre. A tight ICF house needs much less; if yours needs half, halve the last column.
| Heat source | Installed range | Cents per delivered kWh | 18,000 kWh a year | Can it cool? |
|---|---|---|---|---|
| Condensing gas boiler, heating only | $5,500 to $11,000 | 4.6 | about $828 | No |
| Condensing gas combi, heat and hot water | $5,000 to $10,000 | 4.6 | about $828 | No |
| Air-to-water heat pump plant | $15,000 to $35,000 and up | 6.4 at COP 2.5, 5.0 at COP 3.2 | about $1,152 to $900 | Yes, with fan coils |
| Geothermal, water-to-water | $25,000 to $55,000 and up | site-specific | see the geothermal pages | Yes, with fan coils |
| Electric boiler, resistance, COP 1 | quoted; check the panel first | 16 | about $2,880 | No |
| Propane boiler, 95 percent, for comparison | quoted | 13.3 | about $2,394 | No |
Why Ontario prices are all over the map: the contractors and price guides we checked disagreed on almost every line of this table. On a combi, one price guide says $3,500 to $10,000 and up and our own page says $5,000 to $8,000; on the radiant floor itself it is $6 to $12 a square foot on our page against $8 to $15 in a Toronto contractor’s guide; and on air-to-water, a Toronto contractor’s guide says $15,000 to $35,000 and up with nobody publishing anything tighter. The equipment, the controls, whether the manifolds are in, and who is quoting move it. Budget $8,000 for a condensing boiler and get two or three quotes on the same written scope.
Gas works out to $0.45 / 10.4 / 0.95, about 4.6 cents a delivered kWh. The gas customer charge, about $25 to $30 a month, is fixed whether you burn gas or not, so $300 to $360 a year comes with the meter. The method is on the gas vs heat pump operating cost page.
Condensing Boiler or Combi: the Cheap, Proven Answer Where Gas Is at the Road
A condensing gas boiler is the cheapest installed answer and, on today’s prices, the cheapest to run. Radiant floors suit it well, because a condensing boiler is most efficient with cool water coming back to it, and a slab sends back cool water all winter. A combi is the same boiler with the domestic hot water built in, about $500 less on the budget numbers and one appliance instead of two; the combi vs tankless page covers that choice.
Neither one cools. A radiant house with a boiler still needs a cooling plan and an HRV, so the true budget is the boiler plus a ductless head or two, or a small ducted air handler. People forget that line more than any other on a radiant house.
Air-to-Water and Geothermal: More Money Up Front, Cooling Thrown In
An air-to-water heat pump makes low-temperature water, which is exactly what a slab wants, and many can make chilled water for fan coils in summer. On the arithmetic above it costs about $324 a year more to run than gas at a seasonal COP of 2.5 and about the same at 3.2, and it gets rid of the gas meter and its fixed charge. It costs two to four times what a boiler does to install and needs a buffer tank, backup and a proper design. The air-to-water page goes through all of it.
Geothermal does the same job from the ground instead of the air, with better winter efficiency and a much bigger cheque for the loop. The ICF and geothermal combination is a good one, and the geothermal cost page prices it properly, site by site, so I will not re-price it here.
Electric Boiler: Simple, Small, and the Bill Says Why Nobody Picks It
An electric boiler has no flame, no vent and no gas line, and it hangs on the wall in about the space of a briefcase. At 16 cents a kWh and a COP of 1, though, it is the dearest heat on the table: about $2,880 for 18,000 kWh. It makes sense in a very small, very tight space, a garage slab, or as the backup inside a heat pump system. The real question is the electrical service: a whole-house electric boiler on a 100 A panel is often a $2,500 to $4,500 panel upgrade before it is anything else.
What I Would Install, and Where People Go Wrong
- Gas at the road, normal budget: a condensing combi or boiler on the slab, an HRV, and a ductless head or two for summer. Cheap to buy, cheap to run, nothing exotic to fix.
- No gas, propane only: look hard at air-to-water. At 13.3 cents a kWh, propane is where a heat pump wins easily, and the extra install cost has somewhere to come back from.
- All-electric by choice, tight house: air-to-water with a sensible backup, or geothermal if the lot and the budget allow. Size it from a CSA F280 heat loss, not the square footage.
- Do not oversize anything. A tight house loses about half what the same house in frame does. A big boiler on a small house short-cycles like a car driven only to the end of the driveway.
- Gas means a TSSA-registered contractor with a certified gas technician, venting and makeup air checked after any air sealing, and a CO alarm on every floor.
Questions people ask
What is the cheapest heat source for radiant floor heating in Ontario?
On today’s prices, a condensing gas boiler or combi, both to install, $5,500 to $11,000 or $5,000 to $10,000, and to run, about 4.6 cents per delivered kWh. Without gas, an air-to-water heat pump beats propane and electric resistance by a wide margin on running cost.
Is a heat pump good for radiant floors?
Yes, better than for almost anything else, because a slab runs on low-temperature water and that is where a heat pump is most efficient. It needs a proper design, a buffer tank and backup for minus 25 C.
Can I use an electric boiler for my whole house?
You can, and it costs about $2,880 a year to deliver 18,000 kWh of heat at 16 cents. Check the electrical service first; many houses need a 200 A upgrade at $2,500 to $4,500.
Which radiant heat sources can also cool?
Air-to-water and geothermal water-to-water units can make chilled water for fan coils or a small air handler. Boilers, combis and electric boilers cannot, so those houses need a separate cooling plan.
Run your own house through all five
The HVAC system cost comparison calculator takes your house and your rates and prices five systems side by side, installed and over 15 years. If you have quotes for a radiant heat source, the $99 review reads up to three of them and says which one I would sign.
Sources and further reading
- Heating and Cooling With a Heat Pump: Natural Resources Canada: how air-source, ductless, ground-source and air-to-water heat pumps work in a Canadian climate, sizing, backup heat and balance points.
- Ontario Energy Board: electricity prices from November 1, 2026: the time-of-use, ultra-low overnight and tiered prices and the Ontario Electricity Rebate rate used in the operating cost arithmetic.
- Enbridge Gas Ontario rates: the current gas supply, transportation and delivery charges and the monthly customer charge.
